Apparatuses and methods for the production of microfibers and nanofibers

ABSTRACT

Described herein are apparatuses and methods of creating fibers, such as microfibers and nanofibers. The methods discussed herein employ centrifugal forces to transform material into fibers. Apparatuses that may be used to create fibers are also described.

PRIORITY CLAIM

This application claims the benefit of U.S. Provisional Application No.61/620,298 filed on Apr. 4, 2012.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to the field of fiberproduction. More specifically, the invention relates to production offibers of micron, sub-micron and nano size diameters using centrifugalforces.

2. Description of the Relevant Art

Fibers having small diameters (e.g., micrometer (“micron”) to nanometer(“nano”)) are useful in a variety of fields from the clothing industryto military applications. For example, in the biomedical field, there isa strong interest in developing structures based on nanofibers thatprovide scaffolding for tissue growth to effectively support livingcells. In the textile field, there is a strong interest in nanofibersbecause the nanofibers have a high surface area per unit mass thatprovide light, but highly wear resistant, garments. As a class, carbonnanofibers are being used, for example, in reinforced composites, inheat management, and in reinforcement of elastomers. Many potentialapplications for small-diameter fibers are being developed as theability to manufacture and control their chemical and physicalproperties improves.

It is well known in fiber manufacturing to produce micro and nano fibersof various materials by electrospinning The process of elecrospinninguses an electrical charge to produce fibers from a liquid. The liquidmay be a solution of a material in a suitable solvent, or a melt of thematerial. Electrospinning requires the use of high voltage to draw outthe fibers and is limited to materials that can obtain an electricalcharge.

Centrifugal spinning is a method by which fibers are produced withoutthe use of an electric field. In centrifugal spinning, material isejected through one or more orifices of a rapidly spinning spinneret toproduce fibers. The size and or shape of the orifice that the materialis ejected from controls the size of the fibers produced. Usingcentrifugal spinning, microfibers and/or nanofibers may be produced.

Typically, spinnerets used in centrifugal spinning are rotated at highspeeds. The high rotational speed used to form the fibers creates highenergy requirements, due to rotational air resistance at high speeds. Itis desirable to create spinnerets that have reduced air resistance tominimize energy requirements. Additionally, spinnerets generally producefibers in a single plane, which causes fiber entanglement. It wouldtherefore be desirable to create spinnerets that can create fibers in away that avoids entanglement of the fibers that can maximize yield andenhance uniform fiber deposition if desired, and are easily cleaned.

SUMMARY OF THE INVENTION

Described herein are apparatuses and methods of creating fibers, such asmicrofibers and nanofibers. The methods discussed herein employcentrifugal forces to transform material into fibers. In one embodimenta fiber producing system includes a fiber producing device and a drivercapable of rotating the fiber producing device. The fiber producingdevice, in one embodiment, includes a body having one or more openingsand a coupling member, wherein the body is configured to receivematerial to be produced into a fiber. The body of the fiber producingdevice is couplable to the driver through the coupling member. Duringuse rotation of the fiber producing device coupled to the driver causesmaterial in the body to be passed through one or more openings toproduce microfibers and/or nanofibers.

In an embodiment, a device for use in a microfiber and/or nanofiberproducing system, the device includes: a body comprising a body cavityand a coupling member, wherein the body cavity is configured to receivematerial to be produced into a fiber, wherein the body is couplable to adriver through the coupling member; and at least two blades extendingfrom the body, wherein each of the blades comprises a blade cavitycoupled to the body cavity, wherein material to be produced into a fiberpasses from the body cavity to the blade cavity during use, and whereinone or more openings are formed at or proximate to an end of each bladeextending through a side wall of the blade. During use, rotation of thebody causes material in the body to be ejected through one or moreopenings to produce microfibers and/or nanofibers.

In an embodiment, the fiber producing device may include a first memberand a second member. The first member includes: a first member centralportion; at least two arms extending from the first member centralportion; a first member coupling surface formed along an edge of thefirst member central portion and the arms extending from the firstmember central portion; and one or more grooves formed in the firstmember coupling surface, proximate to an end of the arms. The secondmember includes: a second member comprising: a second member centralportion; at least two arms extending from a second member centralportion; a second member coupling surface formed along an edge of thesecond member central portion and the arms extending from the secondmember central portion; and one or more grooves formed in the firstmember coupling surface, proximate to an end of the arms, wherein thefiber producing device is couplable to a driver through the couplingmember. The first member coupling surface is coupled to the secondmember coupling surface to form the fiber producing device. The firstmember central portion and the second member central portion combine toform the body, and at least two of the first member arms couple to atleast two of the second member arms to form the at least two bladesextending from the body. One or more grooves of the first member armsare substantially aligned with the one or more grooves of thecorresponding second member arms to form one or more openings extendingthrough side walls of the formed blades.

In an alternate embodiment, the fiber producing device may include afirst member and a second member. The first member includes: a firstmember central portion; at least two arms extending from the firstmember central portion; a first member coupling surface formed along anedge of the first member central portion and the arms extending from thefirst member central portion; and one or more openings extending througha sidewall of each of the arms of the first member, proximate to an endof the arms. The second member includes: a second member centralportion; at least two arms extending from a second member centralportion; a second member coupling surface formed along an edge of thesecond member central portion and the arms extending from the secondmember central portion; the coupling member coupled to the second membercentral portion; wherein the fiber producing device is couplable to adriver through the coupling member. The first member coupling surface iscoupled to the second member coupling surface to form the fiberproducing device. The first member central portion and the second membercentral portion combine to form the body, and at least two of the firstmember arms couple to at least two of the second member arms to form theat least two blades extending from the body.

In an alternate embodiment, the fiber producing device may include afirst member and a second member. The first member includes: a firstmember central portion; at least two arms extending from the firstmember central portion; a first member coupling surface formed along anedge of the first member central portion and the arms extending from thefirst member central portion; and one or more openings extending througha sidewall of each of the first member arms, proximate to an end of thearms. The second member includes: a second member central portion; atleast two arms extending from a second member central portion; a secondmember coupling surface formed along an edge of the second membercentral portion and the arms extending from the second member centralportion; and one or more openings extending through a sidewall of eachof the second member arms, proximate to an end of the arms. The firstmember coupling surface is coupled to the second member coupling surfaceto form the fiber producing device. The first member central portion andthe second member central portion combine to form the body, and at leasttwo of the first member arms couple to at least two of the second memberarms to form the at least two blades extending from the body.

The driver may be positioned below the fiber producing device or abovethe fiber producing device, when the fiber producing device is coupledto the driver. The driver may be capable of rotating the fiber producingdevice at speeds of greater than about 1000 RPM

The fiber producing device may be enclosed in a chamber, wherein theenvironment inside the chamber is controllable. A fiber producing systemmay include a collection system surrounding at least a portion of thefiber producing device, wherein fibers produced during use are at leastpartially collected on the collection system. In one embodiment, aheating device is thermally coupled to the fiber producing device.

In another embodiment a fiber producing device includes: a bodycomprising a body cavity and a coupling member, wherein the body cavityis configured to receive material to be produced into a fiber, whereinthe body is couplable to a driver through the coupling member; at leasttwo blades extending from the body, wherein each of the blades comprisesa blade cavity coupled to the body cavity, and a porous materialpositioned proximate to an end of at least one blade, wherein the porousmaterial comprises one or more passages that allow a liquid to passthrough the porous material. The material to be produced into a fiberpasses from the body cavity to the blade cavity and through the porousmaterial during use. The rotation of the body causes material in thebody to be ejected through the porous material to produce microfibersand/or nanofibers.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will become apparent to thoseskilled in the art with the benefit of the following detaileddescription of embodiments and upon reference to the accompanyingdrawings in which:

FIG. 1 depicts an exploded view of an embodiment of a fiber producingdevice;

FIG. 2 depicts a projection view of the assembled fiber producing deviceof FIG. 1;

FIG. 3 depicts a side view of the assembled fiber producing device ofFIG. 1;

FIG. 4 depicts a side view of a fiber producing device having aplurality of levels of openings;

FIG. 5 depicts a side view of a fiber producing device having a microporous material; and

FIG. 6 depicts a projection view of a fiber producing system.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Thedrawings may not be to scale. It should be understood, however, that thedrawings and detailed description thereto are not intended to limit theinvention to the particular form disclosed, but to the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the present invention as definedby the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood the present invention is not limited toparticular devices or methods, which may, of course, vary. It is also tobe understood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting. As used in this specification and the appended claims, thesingular forms “a”, “an”, and “the” include singular and pluralreferents unless the content clearly dictates otherwise. Furthermore,the word “may” is used throughout this application in a permissive sense(i.e., having the potential to, being able to), not in a mandatory sense(i.e., must). The term “include,” and derivations thereof, mean“including, but not limited to.” The term “coupled” means directly orindirectly connected.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a method or apparatusthat “comprises,” “has,” “includes” or “contains” one or more steps orelements possesses those one or more steps or elements, but is notlimited to possessing only those one or more steps or elements.Likewise, an element of an apparatus that “comprises,” “has,” “includes”or “contains” one or more features possesses those one or more features,but is not limited to possessing only those one or more features.

Described herein are apparatuses and methods of creating fibers, such asmicrofibers and nanofibers. The methods discussed herein employcentrifugal forces to transform material into fibers. Apparatuses thatmay be used to create fibers are also described. Some details regardingcreating fibers using centrifugal forces may be found in the followingU.S. Published Patent Applications: 2009/0280325 entitled “Methods andApparatuses for Making Superfine Fibers” to Lozano et al.; 2009/0269429entitled “Superfine Fiber Creating Spinneret and Uses Thereof” to Lozanoet al.; 2009/0232920 entitled “Superfine Fiber Creating Spinneret andUses Thereof” to Lozano et al.; and 2009/0280207 entitled “SuperfineFiber Creating Spinneret and Uses Thereof” to Lozano et al., all ofwhich are incorporated herein by reference.

An embodiment of a fiber producing device is depicted in FIGS. 1-3.Fiber producing device 100 includes a first member 110 and a secondmember 120. First member 110 includes a first member coupling surface112. At least two arms 115 a and 115 b extend from central portion 118.First member coupling surface 112 includes one or more grooves (notshown) formed in the arms 115 a and 115 b. Second member 120 includes asecond member coupling surface 122 and a coupling member 130. At leasttwo arms 125 a and 125 b extend from central portion 128 of secondmember 120. Second member coupling surface 122 includes one or moregrooves 124 formed in the arms 125 a and 125 b. Coupling member 130 maybe used to couple the fiber producing device to a driver of a fiberproducing system.

The body is formed by coupling first member 110 to second member 120, asdepicted in FIG. 2. To couple the first and second members, first membercoupling surface 112 is contacted with second member coupling surface122. One or more fasteners 150 may be used to secure the first memberand second member together. When the first member coupling surface iscoupled to the second member coupling surface, the first member centralportion 118 couples with second member central portion 128 to define abody 140 having an internal cavity 144.

When the grooves of the first member are aligned with the grooves of thesecond member, the grooves together form one or more openings 160extending from the interior cavity to an outer surface of the body, asdepicted in FIG. 3. During use, rotation of the body material disposedin the internal cavity of the body is ejected through one or moreopenings 150 to produce microfibers and/or nanofibers. Material may beplaced into the body of fiber producing through a first member opening155 formed in first member 110.

A fiber producing device that includes two or more arms offers a numberof advantages over prior devices. The angled design of the blades allowsthe openings 160 to be located at different planes, minimizing theprobability of fiber entanglement (bundling) as the material isexpelled. In some embodiments, the blades are set at a pitch of betweenabout 10° to about 20° with respect to a longitudinal plane runningperpendicular to the body. In the embodiment depicted in FIG. 2, thefiber producing device includes two opposing blades 170 and 175 set at apitch of about 12° with respect to a longitudinal plane runningperpendicular to the body.

In some embodiments, the blades 170 and 175 may have an aerodynamicprofile. The aerodynamics of the bladed fiber producing device providean improved aerodynamic force that allows for the fibers to be guidedoutward and away from the fiber producing device. This outward forcehelps to inhibit pull-back of the produced fibers onto the spinneret.This, in turn, also aids in the prevention of fiber entanglement andpromotes homogenous deposition of fibers. The aerodynamics of the fiberproducing device also serves to direct the fibers in the axial directionof the spinneret for deposition purposes.

As shown in FIGS. 1-3, the fiber producing device is made in two partsthat are joined together. Having two components allows for ease ofassembly and clean up of the fiber producing device.

An alternate embodiment of a fiber producing device is depicted in FIG.4. Fiber producing device 200 is formed from a first member 210 and asecond member 220 as described above. Fiber producing device 200 differsfrom the devices depicted in FIGS. 1-3 by including additional rows 252and 254 of openings that are formed in the side walls of the blades.Openings 250 are optionally present and are formed by the alignment ofgrooves formed in the first and second members (210, 220). The use ofmultiple rows of openings allows improved distribution of producedfibers.

In an alternate embodiment, a porous material 320 may be disposed at theouter surface of a blade 310 of a fiber producing device 300 as depictedin FIG. 5. A porous material may be any material that includes one ormore passages that allow a liquid (a solution or a molten material) topass through the material. The porous material may be positioned betweenthe first member and the second member at an outer surface of the bladesuch that one or more of the passages allow a liquid disposed in theinternal cavity of the central body to flow through the formed blades. Aporous material may be a ceramic, polymeric, or metal material having aplurality of interconnecting pores passing through the material.Alternately, a porous material may be a substantially non-porousceramic, polymer, or metal material having a plurality of openings thatextend through the material. For example, a metal insert may have aplurality of machined holes formed through the metal insert. The metalinsert may be disposed in a receiving sections 325 a, 325 b of the arms.

In an embodiment, where the fiber producing device is coupled to adriver positioned above the fiber producing device, the coupling memberextends through the internal cavity defined by the first and secondmembers and through the first member. Alternatively, where the fiberproducing device is coupled to a driver positioned below the fiberproducing device, the coupling member is coupled to an outer surface ofthe second member, extending away from the second member.

Fibers created using the fiber producing devices described herein may becollected using a variety of fiber collection devices. Various exemplaryfiber collection devices are discussed below, and each of these devicesmay be combined with one another. The simplest method of fibercollection is to collect the fibers on the interior of a collection wallthat surrounds a fiber producing device. Fibers are typically collectedfrom collection walls as nonwoven fibers.

The aerodynamic flow within the chamber influences the design of thefiber collection device (e.g., height of a collection wall or rod;location of same). The spinning fiber producing device develops anaerodynamic flow within the confinement of the apparatuses describedherein. This flow may be influenced by, for example, the speed, size andshape of the fiber producing device as well as the location, shape, andsize of the fiber collection device. An intermediate wall placed outsidethe collection wall may also influence aerodynamic flow. Theintermediate wall may influence the aerodynamic flow by, for example,affecting the turbulence of the flow. Placement of an intermediate wallmay be necessary in order to cause the fibers to collect on the fibercollection device. In certain embodiments, placement of an intermediatewall can be determined through experimentation. In an embodiment, afiber producing device is operated in the presence of a fiber collectiondevice and an intermediate wall, observing whether or not fibers arecollected on the fiber collection device. If fibers are not adequatelycollected on the fiber collection device, the position of theintermediate wall is moved (e.g., making its diameter smaller or larger,or making the intermediate wall taller or shorter) and the experiment isperformed again to see if adequate collection of fibers is achieved.Repetition of this process may occur until fibers are adequatelycollected on the fiber collection device.

Typically, fibers are collected on a collection wall or settle ontoother designed structure(s). Temperature also plays a role on the sizeand morphology of the formed fibers. If the collection wall, forexample, is relatively hotter than the ambient temperature, fiberscollected on the collection wall may coalesce, leading to bundling ofand/or welding of individual fibers. In some embodiments, thetemperature of the collection wall and/or intermediate wall may becontrolled, such as, for example, by blowing gas (e.g., air, nitrogen,argon, helium) between the intermediate wall and the collection wall. Bycontrolling the flow rate, type, and temperature of this blowing gas, itis possible to control the temperature and morphology of the fibers.Wall parameters (e.g., height, location, etc.) may also influence themorphology of the fibers.

FIG. 6 shows a projection view of a fiber producing system that includesa fiber producing device 100 and a collection wall 400. As depicted,fiber producing device 100 is spinning clockwise about a spin axis, andmaterial is exiting openings of the blades as fibers 420. The fibers arebeing collected on the interior of the surrounding collection wall 400.

Fibers represent a class of materials that are continuous filaments orthat are in discrete elongated pieces, similar to lengths of thread.Fibers are of great importance in the biology of both plants andanimals, e.g., for holding tissues together. Human uses for fibers arediverse. For example, fibers may be spun into filaments, thread, string,or rope. Fibers may also be used as a component of composite materials.Fibers may also be matted into sheets to make products such as paper orfelt. Fibers are often used in the manufacture of other materials.

Fibers as discussed herein may be created using, for example, a solutionspinning method or a melt spinning method. In both the melt and solutionspinning methods, a material may be put into a fiber producing devicewhich is spun at various speeds until fibers of appropriate dimensionsare made. The material may be formed, for example, by melting a soluteor may be a solution formed by dissolving a mixture of a solute and asolvent. Any solution or melt familiar to those of ordinary skill in theart may be employed. For solution spinning, a material may be designedto achieve a desired viscosity, or a surfactant may be added to improveflow, or a plasticizer may be added to soften a rigid fiber. In meltspinning, solid particles may comprise, for example, a metal or apolymer, wherein polymer additives may be combined with the latter.Certain materials may be added for alloying purposes (e.g., metals) oradding value (such as antioxidant or colorant properties) to the desiredfibers.

Non-limiting examples of reagents that may be melted, or dissolved orcombined with a solvent to form a material for melt or solution spinningmethods include polyolefin, polyacetal, polyamide, polyester, celluloseether and ester, polyalkylene sulfide, polyarylene oxide, polysulfone,modified polysulfone polymers and mixtures thereof. Non-limitingexamples of solvents that may be used include oils, lipids and organicsolvents such as DMSO, toluene and alcohols. Water, such as de-ionizedwater, may also be used as a solvent. For safety purposes, non-flammablesolvents are preferred.

In either the solution or melt spinning method, as the material isejected from the spinning fiber producing device, thin jets of thematerial are simultaneously stretched and dried or stretched and cooledin the surrounding environment. Interactions between the material andthe environment at a high strain rate (due to stretching) leads tosolidification of the material into fibers, which may be accompanied byevaporation of solvent. By manipulating the temperature and strain rate,the viscosity of the material may be controlled to manipulate the sizeand morphology of the fibers that are created. A wide variety of fibersmay be created using the present methods, including fibers such aspolypropylene (PP) nanofibers. Non-limiting examples of fibers madeusing the melt spinning method include polypropylene, acrylonitrilebutadiene styrene (ABS) and nylon. Non-limiting examples of fibers madeusing the solution spinning method include polyethylene oxide (PEO),indium-tin oxide, vanadium oxide, silicon carbide, cellulose with ionicliquids, and beta-lactams.

The creation of fibers may be done in batch modes or in continuousmodes. In the latter case, material can fed continuously into the fiberproducing device and the process can be continued over days (e.g., 1-7days) and even weeks (e.g., 1-4 weeks).

The methods discussed herein may be used to create, for example,nanocomposites and functionally graded materials that can be used forfields as diverse as, for example, drug delivery and ultrafiltration(such as electrets). Metallic and ceramic nanofibers, for example, maybe manufactured by controlling various parameters, such as materialselection and temperature. At a minimum, the methods and apparatusesdiscussed herein may find application in any industry that utilizesmicro- to nano-sized fibers and/or micro- to nano-sized composites. Suchindustries include, but are not limited to, material engineering,mechanical engineering, military/defense industries, biotechnology,medical devices, tissue engineering industries, food engineering, drugdelivery, electrical industries, or in ultrafiltration and/ormicro-electric mechanical systems (MEMS).

Some embodiments of a fiber producing device may be used for melt and/orsolution processes. Some embodiments of a fiber producing device may beused for making organic and/or inorganic fibers. With appropriatemanipulation of the environment and process, it is possible to formfibers of various configurations, such as continuous, discontinuous,mat, random fibers, unidirectional fibers, woven and nonwoven, as wellas fiber shapes, such as circular, elliptical and rectangular (e.g.,ribbon). Other shapes are also possible. The produced fibers may besingle lumen or multi-lumen.

By controlling the process parameters, fibers can be made in micron,sub-micron and nano-sizes, and combinations thereof. In general, thefibers created will have a relatively narrow distribution of fiberdiameters. Some variation in diameter and cross-sectional configurationmay occur along the length of individual fibers and between fibers.

Generally speaking, a fiber producing device helps control variousproperties of the fibers, such as the cross-sectional shape and diametersize of the fibers. More particularly, the speed and temperature of afiber producing device, as well as the cross-sectional shape, diametersize and angle of the outlets in a fiber producing device, all may helpcontrol the cross-sectional shape and diameter size of the fibers.Lengths of fibers produced may also be influenced by the choice of fiberproducing device used.

The temperature of the fiber producing device may influence fiberproperties, in certain embodiments. Both resistance and inductanceheaters may be used as heat sources to heat a fiber producing device. Incertain embodiments, the fiber producing device is thermally coupled toa heat source that may be used to adjust the temperature of the fiberproducing device before spinning, during spinning, or both beforespinning and during spinning In some embodiments, the fiber producingdevice is cooled. For example, a fiber producing device may be thermallycoupled to a cooling source that can be used to adjust the temperatureof the fiber producing device before spinning, during spinning, orbefore and during spinning Temperatures of a fiber producing device mayrange widely. For example, a fiber producing device may be cooled to aslow as −20 C or heated to as high as 2500 C. Temperatures below andabove these exemplary values are also possible. In certain embodiments,the temperature of a fiber producing device before and/or duringspinning is between about 4° C. and about 400° C. The temperature of afiber producing device may be measured by using, for example, aninfrared thermometer or a thermocouple.

The speed at which a fiber producing device is spun may also influencefiber properties. The speed of the fiber producing device may be fixedwhile the fiber producing device is spinning, or may be adjusted whilethe fiber producing device is spinning Those fiber producing deviceswhose speed may be adjusted may, in certain embodiments, becharacterized as variable speed fiber producing devices. In the methodsdescribed herein, the fiber producing device may be spun at a speed ofabout 500 RPM to about 25,000 RPM, or any range derivable therein. Incertain embodiments, the fiber producing device is spun at a speed of nomore than about 50,000 RPM, about 45,000 RPM, about 40,000 RPM, about35,000 RPM, about 30,000 RPM, about 25,000 RPM, about 20,000 RPM, about15,000 RPM, about 10,000 RPM, about 5,000 RPM, or about 1,000 RPM. Incertain embodiments, the fiber producing device is rotated at a rate ofabout 5,000 RPM to about 25,000 RPM.

In an embodiment, a method of creating fibers, such as microfibersand/or nanofibers, includes: heating a material; placing the material ina heated fiber producing device; and, after placing the heated materialin the heated fiber producing device, rotating the fiber producingdevice to eject material to create nanofibers from the material. In someembodiments, the fibers may be microfibers and/or nanofibers. A heatedfiber producing device is a structure that has a temperature that isgreater than ambient temperature. “Heating a material” is defined asraising the temperature of that material to a temperature above ambienttemperature. “Melting a material” is defined herein as raising thetemperature of the material to a temperature greater than the meltingpoint of the material, or, for polymeric materials, raising thetemperature above the glass transition temperature for the polymericmaterial. In alternate embodiments, the fiber producing device is notheated. Indeed, for any embodiment that employs a fiber producing devicethat may be heated, the fiber producing device may be used withoutheating. In some embodiments, the fiber producing device is heated butthe material is not heated. The material becomes heated once placed incontact with the heated fiber producing device. In some embodiments, thematerial is heated and the fiber producing device is not heated. Thefiber producing device becomes heated once it comes into contact withthe heated material.

A wide range of volumes/amounts of material may be used to producefibers. In addition, a wide range of rotation times may also beemployed. For example, in certain embodiments, at least 5 milliliters(mL) of material are positioned in a fiber producing device, and thefiber producing device is rotated for at least about 10 seconds. Asdiscussed above, the rotation may be at a rate of about 500 RPM to about25,000 RPM, for example. The amount of material may range from mL toliters (L), or any range derivable therein. For example, in certainembodiments, at least about 50 mL to about 100 mL of the material arepositioned in the fiber producing device, and the fiber producing deviceis rotated at a rate of about 500 RPM to about 25,000 RPM for about 300seconds to about 2,000 seconds. In certain embodiments, at least about 5mL to about 100 mL of the material are positioned in the fiber producingdevice, and the fiber producing device is rotated at a rate of 500 RPMto about 25,000 RPM for 10-500 seconds.

In certain embodiments, at least 100 mL to about 1,000 mL of material ispositioned in the fiber producing device, and the fiber producing deviceis rotated at a rate of 500 RPM to about 25,000 RPM for about 100seconds to about 5,000 seconds. Other combinations of amounts ofmaterial, RPMs and seconds are contemplated as well.

Typical dimensions for fiber producing devices are in the range ofseveral inches in diameter (e.g., 3-8″ in diameter) and 1-2″ in height.

In certain embodiments, fiber producing device includes at least oneopening and the material is extruded through the opening to create thenanofibers. In certain embodiments, the fiber producing device includesmultiple openings and the material is extruded through the multipleopenings to create the nanofibers. These openings may be of a variety ofshapes (e.g., circular, elliptical, rectangular, square) and of avariety of diameter sizes (e.g., 0.01-0.80 mm). When multiple openingsare employed, not every opening need be identical to another opening,but in certain embodiments, every opening is of the same configuration.Some opens may include a divider that divides the material, as thematerial passes through the openings. The divided material may formmulti-lumen fibers.

In an embodiment, material may be positioned in a reservoir of a fiberproducing device. The reservoir may, for example, be defined by a cavityof the heated structure. In certain embodiments, the heated structureincludes one or more openings in communication with the concave cavity.The fibers are extruded through the opening while the fiber producingdevice is rotated about a spin axis. The one or more openings have anopening axis that is not parallel with the spin axis. The fiberproducing device may include a body that includes the concave cavity anda lid positioned above the body.

Another fiber producing device variable includes the material(s) used tomake the fiber producing device. Fiber producing devices may be made ofa variety of materials, including metals (e.g., brass, aluminum,stainless steel) and/or polymers. The choice of material depends on, forexample, the temperature the material is to be heated to, or whethersterile conditions are desired.

Any method described herein may further comprise collecting at leastsome of the microfibers and/or nanofibers that are created. As usedherein “collecting” of fibers refers to fibers coming to rest against afiber collection device. After the fibers are collected, the fibers maybe removed from a fiber collection device by a human or robot. A varietyof methods and fiber (e.g., nanofiber) collection devices may be used tocollect fibers.

Regarding the fibers that are collected, in certain embodiments, atleast some of the fibers that are collected are continuous,discontinuous, mat, woven, nonwoven or a mixture of theseconfigurations. In some embodiments, the fibers are not bundled into acone shape after their creation. In some embodiments, the fibers are notbundled into a cone shape during their creation. In particularembodiments, fibers are not shaped into a particular configuration, suchas a cone figuration, using gas, such as ambient air, that is blown ontothe fibers as they are created and/or after they are created.

Present method may further comprise, for example, introducing a gasthrough an inlet in a housing, where the housing surrounds at least theheated structure. The gas may be, for example, nitrogen, helium, argon,or oxygen. A mixture of gases may be employed, in certain embodiments.

The environment in which the fibers are created may comprise a varietyof conditions. For example, any fiber discussed herein may be created ina sterile environment. As used herein, the term “sterile environment”refers to an environment where greater than 99% of living germs and/ormicroorganisms have been removed. In certain embodiments, “sterileenvironment” refers to an environment substantially free of living germsand/or microorganisms. The fiber may be created, for example, in avacuum. For example the pressure inside a fiber producing system may beless than ambient pressure. In some embodiments, the pressure inside afiber producing system may range from about 1 millimeters (mm) ofmercury (Hg) to about 700 mm Hg. In other embodiments, the pressureinside a fiber producing system may be at or about ambient pressure. Inother embodiments, the pressure inside a fiber producing system may begreater than ambient pressure. For example the pressure inside a fiberproducing system may range from about 800 mm Hg to about 4 atmospheres(atm) of pressure, or any range derivable therein.

In certain embodiments, the fiber is created in an environment of 0-100%humidity, or any range derivable therein. The temperature of theenvironment in which the fiber is created may vary widely. In certainembodiments, the temperature of the environment in which the fiber iscreated can be adjusted before operation (e.g., before rotating) using aheat source and/or a cooling source. Moreover, the temperature of theenvironment in which the fiber is created may be adjusted duringoperation using a heat source and/or a cooling source. The temperatureof the environment may be set at sub-freezing temperatures, such as −20°C., or lower. The temperature of the environment may be as high as, forexample, 2500° C.

The material employed may include one or more components. The materialmay be of a single phase (e.g., solid or liquid) or a mixture of phases(e.g., solid particles in a liquid). In some embodiments, the materialincludes a solid and the material is heated. The material may become aliquid upon heating. In another embodiment, the material may be mixedwith a solvent. As used herein a “solvent” is a liquid that at leastpartially dissolves the material. Examples of solvents include, but arenot limited to, water and organic solvents. Examples of organic solventsinclude, but are not limited to: hexanes, ether, ethyl acetate, acetone,dichloromethane, chloroform, toluene, xylenes, petroleum ether,dimethylsulfoxide, dimethylformamide, or mixtures thereof. Additives mayalso be present. Examples of additives include, but are not limited to:thinners, surfactants, plasticizers, or combinations thereof

The material used to form the fibers may include at least one polymer.Examples of polymers that may be used include, but are not limited topolypropylenes, polyethylenes, polystyrenes, polyesters, fluorinatedpolymers, polyamides, polyaramids, acrylonitrile butadiene styrene,nylons, polycarbonates, or any combination thereof. The polymer may be asynthetic (man-made) polymer or a natural polymer. The material used toform the fibers may be a composite of different polymers or a compositeof a medicinal agent combined with a polymeric carrier. Specificpolymers that may be used include, but are not limited to chitosan,nylon, nylon-6, PAN, PLA, PCL, silk, collagen, PMMA, PLGA, PLA,polyglycolic acid (PGA), polyglactin, and polydioxanone.

In another embodiment, the material used to form the fibers may includeat least one metal. Metals employed in fiber creation include, but arenot limited to, bismuth, tin, zinc, silver, gold, nickel, aluminum, orcombinations thereof. The material used to form the fibers may include,for example, at least one ceramic, such as alumina, titania, silica,zirconia, or combinations thereof. The material used to form the fibersmay be a composite of different metals (e.g., an alloy such as nitonol),a metal/ceramic composite or a ceramic oxides (e.g., PVP withgermanium/palladium/platinum).

The fibers that are created may be, for example, one micron or longer inlength. For example, created fibers may be of lengths that range fromabout 1 μm to about 50 cm, from about 100 μm to about 10 cm, or fromabout 1 mm to about 1 cm. In some embodiments, the fibers may have anarrow length distribution. For example, the length of the fibers may bebetween about 1 μm to about 9 μm, between about 1 mm to about 9 mm, orbetween about 1 cm to about 9 cm. In some embodiments, when continuousmethods are performed, fibers of up to about 10 meters, up to about 5meters, or up to about 3 meters in length may be formed.

In certain embodiments, the cross-section of the fiber may be circular,elliptical or rectangular. Other shapes are also possible. The fiber maybe a single-lumen fiber or a multi-lumen fiber.

In another embodiment of a method of creating a fiber, the methodincludes: spinning material to create the fiber; where, as the fiber isbeing created, the fiber is not subjected to an externally-appliedelectric field or an externally-applied gas; and the fiber does not fallinto a liquid after being created.

Fibers discussed herein are a class of materials that exhibit an aspectratio of at least 100 or higher. The term “microfiber” refers to fibersthat have a minimum diameter in the range of 10 microns to 700nanometers, or from 5 microns to 800 nanometers, or from 1 micron to 700nanometers. The term “nanofiber” refers to fibers that have a minimumdiameter in the range of 500 nanometers to 1 nanometer; or from 250nanometers to 10 nanometers, or from 100 nanometers to 20 nanometers.

While typical cross-sections of the fibers are circular or elliptic innature, they can be formed in other shapes by controlling the shape andsize of the openings in a fiber producing device (described below).Non-limiting examples of materials that may be used to form fibersinclude polymers (natural or synthetic), polymer blends, biomaterials(e.g., biodegradable and bioresorbable materials), metals, metallicalloys, ceramics, composites and carbon fibers. Non-limiting examples ofspecific fibers made using methods and apparatuses as discussed hereininclude polypropylene (PP), acrylonitrile butadiene, styrene (ABS),nylon, bismuth, polyethylene oxide (PEO) and beta-lactam fibers. Fibersmay include a blending of multiple materials. Fibers may also includeholes (e.g., lumen or multi-lumen) or pores. Multi-lumen fibers may beachieved by, for example, designing one or more exit openings to possessconcentric openings. In certain embodiments, such openings may includesplit openings (that is, wherein two or more openings are adjacent toeach other; or, stated another way, an opening possesses one or moredividers such that two or more smaller openings are made). Such featuresmay be utilized to attain specific physical properties, such as thermalinsulation or impact absorbance (resilience). Nanotubes may also becreated using methods and apparatuses discussed herein.

Fibers may be analyzed via any means known to those of skill in the art.For example, Scanning Electron Microscopy (SEM) may be used to measuredimensions of a given fiber. For physical and materialcharacterizations, techniques such as differential scanning calorimetry(DSC), thermal analysis (TA) and chromatography may be used.

In this patent, certain U.S. patents, U.S. patent applications, andother materials (e.g., articles) have been incorporated by reference.The text of such U.S. patents, U.S. patent applications, and othermaterials is, however, only incorporated by reference to the extent thatno conflict exists between such text and the other statements anddrawings set forth herein. In the event of such conflict, then any suchconflicting text in such incorporated by reference U.S. patents, U.S.patent applications, and other materials is specifically notincorporated by reference in this patent.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the invention. It is to beunderstood that the forms of the invention shown and described hereinare to be taken as examples of embodiments. Elements and materials maybe substituted for those illustrated and described herein, parts andprocesses may be reversed, and certain features of the invention may beutilized independently, all as would be apparent to one skilled in theart after having the benefit of this description of the invention.Changes may be made in the elements described herein without departingfrom the spirit and scope of the invention as described in the followingclaims.

1. A device for use in a microfiber and/or nanofiber producing system,the device comprising: a body comprising a body cavity and a couplingmember, wherein the body cavity is configured to receive material to beproduced into a fiber, wherein the body is couplable to a driver throughthe coupling member; and at least two blades extending from the body,wherein each of the blades comprises a blade cavity coupled to the bodycavity, wherein material to be produced into a fiber passes from thebody cavity to the blade cavity during use, and wherein one or moreopenings are formed at or proximate to an end of each blade extendingthrough a side wall of the blade; wherein, during use, rotation of thebody causes material in the body to be ejected through one or moreopenings to produce microfibers and/or nanofibers.
 2. The device ofclaim 1, wherein the device comprises: a first member comprising: afirst member central portion; at least two arms extending from the firstmember central portion; a first member coupling surface formed along anedge of the first member central portion and the arms extending from thefirst member central portion; and one or more grooves formed in thefirst member coupling surface, proximate to an end of the arms, a secondmember comprising: a second member central portion; at least two armsextending from a second member central portion; a second member couplingsurface formed along an edge of the second member central portion andthe arms extending from the second member central portion; and one ormore grooves formed in the first member coupling surface, proximate toan end of the arms, wherein the fiber producing device is couplable to adriver through the coupling member; wherein the first member couplingsurface is coupled to the second member coupling surface to form thefiber producing device, and wherein the first member central portion andthe second member central portion combine to form the body, and whereinat least two of the first member arms couple to at least two of thesecond member arms to form the at least two blades extending from thebody; wherein the one or more grooves of the first member arms aresubstantially aligned with the one or more grooves of the correspondingsecond member arms to form one or more openings extending through sidewalls of the formed blades.
 3. The device of claim 1, wherein the devicecomprises: a first member comprising: a first member central portion; atleast two arms extending from the first member central portion; a firstmember coupling surface formed along an edge of the first member centralportion and the arms extending from the first member central portion;and one or more openings extending through a sidewall of each of thearms of the first member, proximate to an end of the arms, a secondmember comprising: a second member central portion; at least two armsextending from a second member central portion; a second member couplingsurface formed along an edge of the second member central portion andthe arms extending from the second member central portion; the couplingmember coupled to the second member central portion; wherein the fiberproducing device is couplable to a driver through the coupling member;wherein the first member coupling surface is coupled to the secondmember coupling surface to form the fiber producing device, and whereinthe first member central portion and the second member central portioncombine to form the body, and wherein at least two of the first memberarms couple to at least two of the second member arms to form the atleast two blades extending from the body.
 4. The device of claim 1,wherein the device comprises: a first member comprising: a first membercentral portion; at least two arms extending from the first membercentral portion; a first member coupling surface formed along an edge ofthe first member central portion and the arms extending from the firstmember central portion; and one or more openings extending through asidewall of each of the first member arms, proximate to an end of thearms, a second member comprising: a second member central portion; atleast two arms extending from a second member central portion; a secondmember coupling surface formed along an edge of the second membercentral portion and the arms extending from the second member centralportion; and one or more openings extending through a sidewall of eachof the second member arms, proximate to an end of the arms; wherein thefirst member coupling surface is coupled to the second member couplingsurface to form the fiber producing device, and wherein the first membercentral portion and the second member central portion combine to formthe body, and wherein at least two of the first member arms couple to atleast two of the second member arms to form the at least two bladesextending from the body.
 5. The device of claim 1, wherein the devicehas two blades extending from opposing sides of the body.
 6. The deviceof claim 1, wherein the blades are set at a pitch of between about 5° toabout 30° with respect to a longitudinal plane running perpendicular tothe body.
 7. The device of claim 1, wherein the blades have anaerodynamic profile.
 8. A microfiber and/or nanofiber producing systemcomprising: a fiber producing device comprising: a body comprising abody cavity and a coupling member, wherein the body cavity is configuredto receive material to be produced into a fiber, wherein the body iscouplable to a driver through the coupling member; and at least twoblades extending from the body, wherein each of the blades comprises ablade cavity coupled to the body cavity, wherein material to be producedinto a fiber passes from the body cavity to the blade cavity during use,and wherein one or more openings are formed at or proximate to an end ofeach blade extending through a side wall of the blade; wherein, duringuse, rotation of the body causes material in the body to be ejectedthrough one or more openings to produce microfibers and/or nanofibers; adriver capable of rotating the fiber producing device, wherein the bodyof the fiber producing device is couplable to the driver through thecoupling member; and wherein, during use, rotation of the body causesmaterial in the body to be ejected through one or more openings toproduce microfibers and/or nanofibers.
 9. The system of claim 8, whereinthe device comprises: a first member comprising: a first member centralportion; at least two arms extending from the first member centralportion; a first member coupling surface formed along an edge of thefirst member central portion and the arms extending from the firstmember central portion; and one or more grooves formed in the firstmember coupling surface, proximate to an end of the arms, a secondmember comprising: a second member central portion; at least two armsextending from a second member central portion; a second member couplingsurface formed along an edge of the second member central portion andthe arms extending from the second member central portion; and one ormore grooves formed in the first member coupling surface, proximate toan end of the arms, wherein the fiber producing device is couplable to adriver through the coupling member; wherein the first member couplingsurface is coupled to the second member coupling surface to form thefiber producing device, and wherein the first member central portion andthe second member central portion combine to form the body, and whereinat least two of the first member arms couple to at least two of thesecond member arms to form the at least two blades extending from thebody; wherein the one or more grooves of the first member arms aresubstantially aligned with the one or more grooves of the correspondingsecond member arms to form one or more openings extending through sidewalls of the formed blades.
 10. The system of claim 8, wherein thedevice comprises: a first member comprising: a first member centralportion; at least two arms extending from the first member centralportion; a first member coupling surface formed along an edge of thefirst member central portion and the arms extending from the firstmember central portion; and one or more openings extending through asidewall of each of the arms of the first member, proximate to an end ofthe arms, a second member comprising: a second member central portion;at least two arms extending from a second member central portion; asecond member coupling surface formed along an edge of the second membercentral portion and the arms extending from the second member centralportion; the coupling member coupled to the second member centralportion; wherein the fiber producing device is couplable to a driverthrough the coupling member; wherein the first member coupling surfaceis coupled to the second member coupling surface to form the fiberproducing device, and wherein the first member central portion and thesecond member central portion combine to form the body, and wherein atleast two of the first member arms couple to at least two of the secondmember arms to form the at least two blades extending from the body. 11.The system of claim 8, wherein the device comprises: a first membercomprising: a first member central portion; at least two arms extendingfrom the first member central portion; a first member coupling surfaceformed along an edge of the first member central portion and the armsextending from the first member central portion; and one or moreopenings extending through a sidewall of each of the first member arms,proximate to an end of the arms, a second member comprising: a secondmember central portion; at least two arms extending from a second membercentral portion; a second member coupling surface formed along an edgeof the second member central portion and the arms extending from thesecond member central portion; and one or more openings extendingthrough a sidewall of each of the second member arms, proximate to anend of the arms; wherein the first member coupling surface is coupled tothe second member coupling surface to form the fiber producing device,and wherein the first member central portion and the second membercentral portion combine to form the body, and wherein at least two ofthe first member arms couple to at least two of the second member armsto form the at least two blades extending from the body.
 12. The systemof claim 8, wherein the device has two blades extending from opposingsides of the body.
 13. The system of claim 8, wherein the blades are setat a pitch of between about 5° to about 30° with respect to alongitudinal plane running perpendicular to the body.
 14. The system ofclaim 8, wherein the blades have an aerodynamic profile.
 15. The systemof claim 8, further comprising a heating device thermally coupled to thefiber producing device.
 16. The system of claim 8, wherein the fiberproducing device is enclosed in a chamber, and wherein the environmentinside the chamber is controllable.
 17. The system of claim 8, whereinthe driver is capable of rotating the fiber producing device at speedsof greater than about 1000 rpm.
 18. The system of claim 8, furthercomprising a collection system surrounding at least a portion of thefiber producing device, wherein fibers produced during use are at leastpartially collected on the collection system.
 19. A method of producingmicrofibers and/or nanofibers, comprising: placing material in a fiberproducing device, the fiber producing device comprising: a bodycomprising a body cavity and a coupling member, wherein the body cavityis configured to receive material to be produced into a fiber, whereinthe body is couplable to a driver through the coupling member; and atleast two blades extending from the body, wherein each of the bladescomprises a blade cavity coupled to the body cavity, wherein material tobe produced into a fiber passes from the body cavity to the blade cavityduring use, and wherein one or more openings are formed at or proximateto an end of each blade extending through a side wall of the blade;wherein, during use, rotation of the body causes material in the body tobe ejected through one or more openings to produce microfibers and/ornanofibers; rotating the fiber producing device at a speed of at leastabout 1000 rpm, wherein rotation of the fiber producing device causesmaterial in the body to be ejected through one or more openings toproduce microfibers and/or nanofibers; and collecting at least a portionof the produced microfibers and/or nanofibers. 20-40. (canceled)